You would need some aerodynamical information about the fans, the rotational speeds, the air density, speed, use/load pattern and turbulence factor of the placement then it's straight forward!
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| Author: | dieselenthusiast [ Sat Mar 29, 2008 11:39 pm ] |
| Post subject: | Electric cooling fans |
Less resistance at highway speeds equals more horsepower and better gas mileage. http://www.flex-a-lite.com/auto/index.html |
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| Author: | Pablo [ Mon Mar 31, 2008 12:59 am ] |
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I have been thinking about this. The mechanical clutch is supposed to be replaced every few years, is it not? I would rather do the electric and wire in a kill switch for water crossing (yeah, I know should not do that... ). So which one is a good choice? What is involved with the electronics? |
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| Author: | Sir Sam [ Mon Mar 31, 2008 1:18 am ] |
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Pablo wrote: I have been thinking about this. The mechanical clutch is supposed to be replaced every few years, is it not? I would rather do the electric and wire in a kill switch for water crossing (yeah, I know should not do that... ).
So which one is a good choice? What is involved with the electronics? No, not really. In my mind electric coolings fans are worthless. In our 300zx world nothing is better than the mechanical fan for moving air. Time and time the issue comes up, and when it comes down to it non of the electric fans move enough air consistently to replace the mechanical fan. |
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| Author: | Reflex [ Mon Mar 31, 2008 3:30 am ] |
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I'm having difficulty seeing how it could increase mileage. If I understand current cooling the fan is part of the mechanical system(ie: just another loop on the belt). That means its tapping a small portion of the kinetic energy being generated by the internal combustion engine. By comparison, an electric fan is going to be powered by the electrical system, which is power that is first generated by combustion, transferred into kinetic, then transferred into electricity before the fan then transfers it back into kinetic. Basic thermodynamics says that there is no way that can be more efficient than simply tapping the initial kinetic energy with your existing mechanical fan, due to losses at each stage of transformation. Maybe I don't understand very well how the existing fans are powered however. |
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| Author: | Sir Sam [ Mon Mar 31, 2008 3:54 am ] |
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Reflex wrote: I'm having difficulty seeing how it could increase mileage. If I understand current cooling the fan is part of the mechanical system(ie: just another loop on the belt). That means its tapping a small portion of the kinetic energy being generated by the internal combustion engine. By comparison, an electric fan is going to be powered by the electrical system, which is power that is first generated by combustion, transferred into kinetic, then transferred into electricity before the fan then transfers it back into kinetic. Basic thermodynamics says that there is no way that can be more efficient than simply tapping the initial kinetic energy with your existing mechanical fan, due to losses at each stage of transformation.
Maybe I don't understand very well how the existing fans are powered however. Yes, I think your logic is sound on that, however the mechanical fan is always spinning, even if you dont need it to, and at best the viscous clutch decreases the energy being transmitted when it need not be. The idea is that electric fan overall reduces drag on the engine, when you do not need air to be sucked through. |
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| Author: | scrambledKJ [ Mon Mar 31, 2008 8:17 am ] |
| Post subject: | fans |
I installed one of Flex-a-lites black magic fans on a YJ. It bolted to the radiator using existing holes. The wiring was neat and simple. You just need a constant hot. The fan will turn itself on and off where you set it too. I can tell you that it was rated at 3300 cfm and when it kicks on, it cools fast. The jeep has a CPI 4.3 Chevy motor slid up to the front of the bay. There is no way the factory 8 blade mechanical fan could move that kind of air. Also, there is no more stress on the waterpump. They call it a waterpump cause it moves water around the block, they don't call it a fan-twirler-thingy. Travis |
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| Author: | Turbowhine [ Mon Mar 31, 2008 9:47 am ] |
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I have pondered the idea of the electric cooling fan also. Mine already has one of the front that runs occasionally during the summer. However, during the winter here in the upper midwest, I have my grill completely blocked off and my temp. gauge runs in the center of the gauge. I would think for about half of the year around here an electric fan would not even run. Joe |
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| Author: | Turbo Tim [ Mon Mar 31, 2008 11:24 am ] |
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Quote: fans
I installed one of Flex-a-lites black magic fans on a YJ. It bolted to the radiator using existing holes. The wiring was neat and simple. You just need a constant hot. The fan will turn itself on and off where you set it too. I can tell you that it was rated at 3300 cfm and when it kicks on, it cools fast. Don't fool yourself. Mechanical fans take more horsepower to run because they move much more air. I have seen claims for electric fans to move 2000+ CFM of air, but if you look at the specs, they do good to move 600CFM. Don’t take my word for it, go to an air conditioning shop and use their tool for balancing air flow in ducts. Measure how much air is going through your radiator with the mechanical and then with the electric. I called one manufacture of electric fans and in teeny-weeny writing their spec is for “Free Air” movement. In the real world, the radiator gets in the way and bigger, longer, and wider blades are needed to move air, and that takes horsepower. |
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| Author: | Reflex [ Mon Mar 31, 2008 12:21 pm ] |
| Post subject: | |
Sir Sam wrote: Yes, I think your logic is sound on that, however the mechanical fan is always spinning, even if you dont need it to, and at best the viscous clutch decreases the energy being transmitted when it need not be.
The idea is that electric fan overall reduces drag on the engine, when you do not need air to be sucked through. So if I understand correctly, the argument for a electric fan is that it dosen't have to run all the time, and as such can save power by being switched off when the engine is cool enough. To know if thats true, I guess someone would have to measure its impact on mileage when on, measure the impact of a mechanical fan, and then determine how much time the fan could be turned off typically. Not an easy proposition. Maybe there is a good way to guesstimate it... |
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| Author: | Sir Sam [ Mon Mar 31, 2008 12:39 pm ] |
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Reflex wrote: Sir Sam wrote: Yes, I think your logic is sound on that, however the mechanical fan is always spinning, even if you dont need it to, and at best the viscous clutch decreases the energy being transmitted when it need not be. The idea is that electric fan overall reduces drag on the engine, when you do not need air to be sucked through. So if I understand correctly, the argument for a electric fan is that it dosen't have to run all the time, and as such can save power by being switched off when the engine is cool enough. To know if thats true, I guess someone would have to measure its impact on mileage when on, measure the impact of a mechanical fan, and then determine how much time the fan could be turned off typically. Not an easy proposition. Maybe there is a good way to guesstimate it... Correct, for example normal non loaded cruising condition at 75 mph really dont require much air to be pulled through, enough air is forced in that a fan isn't really needed, yet your mechanical fan is up there spinning anyway. The downside to this is that generally electric fans do not move as much air as mechanical fans do. Now as for trying to actually determine if that is true, well, I have had enough experience with busted fans and trying to setup electric fans that this is a natural assumption to make and follows logically. However I am willing to admit actually finding a way to measure would be better, though I have little interest in doing this myself because I think that an electric cooling fan would adversely affect cooling capacity. |
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| Author: | Uffe [ Mon Mar 31, 2008 2:08 pm ] |
| Post subject: | |
You would need some aerodynamical information about the fans, the rotational speeds, the air density, speed, use/load pattern and turbulence factor of the placement then it's straight forward!
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| Author: | retmil46 [ Mon Mar 31, 2008 2:49 pm ] |
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Another factor to throw in - if you're running the ORM/SEGR full time, you've significantly reduced the heat load on the cooling system. Correct me if I'm wrong, but don't the gassers have just an electric fan in stock form? That might make a simpler install than an aftermarket fan - rob the stock electric fan off a gasser KJ. A way you could get around possible lower airflow with an electric - you still have the stock electric pusher fan in front. You could wire an aftermarket "puller" fan in with the stock "pusher" fan, such that both are operating at the same time - a pushmepullyou arrangement. |
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| Author: | Turbowhine [ Mon Mar 31, 2008 2:57 pm ] |
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Soemthing else we all need to consider here.... even though our coolant temperatures may be within normal range with the proposed electric fan, what effect might it have on our intercooler for the turbo. That may be an unintended outcome of higher than normal charge are temperatures. Don't get me wrong I was originally in favor of the idea but I have to wonder if it may increase the air temp going to the engine after the cooler robbing fuel economy and power? Joe |
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| Author: | gmctd [ Mon Mar 31, 2008 3:00 pm ] |
| Post subject: | |
Correct - specs from most electric fan vendors is static, free-air flow - closest radiator to the tested fan is in their vehicles in the employee parking lot - the thermo-controlled clutched engine fan in your vehicle does turn at hiway speeds, but it is seldom driven under full hydraulic coupling, and rotation is assisted by hi-pressure airflow thru the radiator - even that continual parasitic loss is way more efficient than power losses of an electric fan(s) selected for max airflow, when the thermo-switch cuts in and the motor(s) starts drawing max current from the battery, resulting in max response from the alternator, resulting in max power loss from the engine - takes more electric power to drive a commensurately spec'ed electric fan than belt-driven power to drive the engine fan - only reason electric fans became prevalent is because of the transverse eng\transaxle packages required by the 'people-mover' concept touted in the '80s - as engine size and btu capacity increased to keep up with increased vehicle size, so did fan motor power, often requiring an auxilliary fan, or two, to keep up - and, oem 180-240amp alternators were often found attached, therein. Thus far with the KJ CRD, no-one has come up with any towing\loading scenario which has fully utilized max oem cooling system capacity, requesting suggestions for additional measures to compensate - IMCO, it's nothing to be concerned about, as the KJ's max real towing capacity is way less than that attainable with the engine in a framed pickup chassis, where a larger radiator would be available - a Diesel engine generates only as much BTU as is required for the job at hand, unlike a gasser (patooie!) engine - observe your ECT guage as it continually rises and falls between 160-190deg, while listening for the roar of a fully thermo\clutch engaged fan, to get a better sense of that concept - you will seldom hear the engine fan, even with ac burning on a hot day, and then only if the KJ is sitting still for extended periods, as in stop\go traffic jams - I prefer the engine-driven fan, any day However, GM\Ford\DCJ have come out with electric viscous fan clutches to more efficiently manage power application and associatied losses in fan drive systems - may be worth looking into, now that they're showing up in boneyards |
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| Author: | gmctd [ Mon Mar 31, 2008 5:25 pm ] |
| Post subject: | |
FYI - while it seems as tho I'm always posting opinion contrary and diametrically opposite to that posted by others, my opinions have been formed from up close and personally having been there - done that over a considerable period of time - to wit: When I was a young lad, long ago tho not so far away, in another century and another time, I distinctly remember when water-cooled infernal combustion engined vehicles each came replete with a four-bladed fan, attached to the water-pump via 4bolts and a spacer, depending on engine\chassis configuration - wanna talk aboutcher parasitic losses! As engine power demand increased and rpms increased to meet those demands, hot-rodders, finding those early fans would sometimes let go, causing much collateral damage, oft removed the offending part - which also resulted in overheating and reduced win ability Along came flex-a-lite, very thin aluminum\ss blades on thicker hub, such that the blades would deflect at higher rpm and higher airflows, reducing load on engine - still with the centrifugal forces, expanding horizons, and collateral damage, but flex-a-lite hung in there, thru the auspices of jcwhitney Strangely, one guy here or there was giving repeated runs and wins with no overheating, but nobody knew how, as the hood was always closed - a fortuitous glimpse revealed a blower motor with a Signal or Emerson electric fan blade attached, mounted behind the radiator - those reciprocating table and floor fans used the same diameter shaft as the heater blower motors in the vehicles, so the adaptation was easy Suddenly came a proliferation of electric fans for racing, even applied to towing and working vehicles Then, with the proliferation of affordable automotive air conditioning, thermo\centrifugal hydraulic clutch fans began showing up on the showroom floor, declutched below spec'ed temp, nearly fully engaged above temp - there went the electric fan market, down the tubes except for the RV trailer crowd, not a very big market as the fan clutches were working for them Hayden began to offer auxilliary eng and trans coolers, and aux electric fans for the towing crowd, but also helpful when instaling large engines in compact cars with small radiators Then, came the self-destruction of those fan clutches when racing: either the housing pulled off the bearing, or pulled the bearing off the shaft, or the bearing froze, wallered the shaft and pulled off, or broke the shaft or the clutch disintegrated at hi-rpm - whether from oem defect: some, design deficiency: some, owner neglect: many - again with the collateral damage Again with the electric fan renaissance - firmly established amongst the limited towing crowd, vehicles had become larger, trailers larger, engines larger, even the oems were offering auxilliary electric fans as part of their towing packages (got the factory towing option aux fan from same vehicle with 454 on my built 6.5LTD GMC crewcab dually) - however, the racing market was larger, so fan technology improved, with more powerful flat pancake-type motors to reduce real estate requirements, molded plastic frames and blades to reduce weight and improve ease of design\configuration Now, you can hit yer local boneyard and find the ideal package to fit your requirements and available real estate, all oem, available everywhere, so you're not stuck on the road in some small one-cylinder town, with no hope for the morrow So, being this is a forum, where all sides of the story should be availiable to facilitate the best decision, I always try to give the other side of the story - the rest of the story - maybe the unknown story, having been there, done that - anyway, that's my story, and I'm stickin' to it - read it if you will, ignore it if you must, but never say "I didn't know"................ |
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| Author: | Pablo [ Mon Mar 31, 2008 7:23 pm ] |
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k. So the clutches don't wear out every few years... check. Will not budget for that. As for no one overheating: I know quite a few in AZ that have had to kill the AC to keep it from overheating. That was offroad in summer, granted. I have not had this issue and with the SEGR doubt I ever will. I think the trans would overheat before the engine most of the time. |
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| Author: | tjkj2002 [ Mon Mar 31, 2008 8:32 pm ] |
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I can't say for the Kj's since mine already only has a electric fan,but on my '84 Blazer I gained over 80HP and 120lbs-ft of torque(at the rear wheels) from removing the mechanical fan and putting on dual Flex-a-lite electric fans,granted at the same time I put in a 36"x26" 5 core aluminum raditor,removed the t-stat,ran straight water with 1 gallon of purple ice,and ceramic coated the headers(headers where installed already just coated them).So it could be mostly from the fact that I reduced my race temps from 230 degrees to 160 degrees that made most of the extra HP and torque,chassied dynoed before and after the mods. |
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| Author: | bbo [ Mon Mar 31, 2008 9:27 pm ] |
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I've got an electric replacement on the S10 ... I can better control the temps ( it has a tstat and a manual switch), but the mechanical did a better job in stop and go driving .. although I don't see much of that at all for extended periods. |
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| Author: | gmctd [ Mon Mar 31, 2008 9:45 pm ] |
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Not really sure why you guys are tossing gasser (patooie!) stuff around in a Diesel forum, but once again - Diesels only generate enuff btu to get a given job done, as illustrated by the rise and fall of your KJ CRD ECT guage, and the fact that Diesels always have much larger fans than those other engines - it has been noted that the standard fan on the GM 6.5LTD generates over 9000cfm at full clutch lockup, and that's behind the radiator, not in free air space, like yer fav electric doodads - no umpteens of 12v electric fans can approach that, even if there were the uncommitted power availability, without loading the serp belt drive. So, kindly leave off with the gasser anecdotes - it's not applicable, here, and doesn't help................. |
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| Author: | tjkj2002 [ Mon Mar 31, 2008 9:56 pm ] |
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gmctd wrote: Not really sure why you guys are tossing gasser (patooie!) stuff around in a Diesel forum, but once again - Diesels only generate enuff btu to get a given job done, as illustrated by the rise and fall of your KJ CRD ECT guage, and the fact that Diesels always have much larger fans than those other engines - it has been noted that the standard fan on the GM 6.5LTD generates over 9000cfm at full clutch lockup - no umpteens of 12v electric fans can approach that, even if there were the uncommitted power availability, without loading the serp belt drive. The fact that a mechanical takes HP to run verses zero HP loss to a electric fan is identical as to pretaining to both gas and desiel engines.The deisel just won't be as effected as a gas engine due to the lower RPM's of the deisel and more torque.
So, kindly leave off with the gasser anecdotes - it's not applicable, here, and doesn't help................. This thread was started about making more power by deleting the mechanical fan,not all the mumbo jumbo about deisels needing this and that to run right. Oh and that 9000cfm from a GM 6.5 is pretty far fetched,worked on the 6.2 and 6.5's(turbo and non-turbo) for 9 years and they don't pull that much CFM,heck with a massive raditor the mechanical fan had major trouble trying to keep the engine temps at 240 degrees,the non-turbo's could maintain at least 200 degrees. |
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